Working on chicken coop design for <-20F temperatures. Need advice for winter ventilation

Hello everyone,

I am new to the forum, but I have been listening to the podcasts for quite a while.

I am currently working on the design of a chicken coop to host a dozen of chickens. It will be a 3.5' x 6' coop with a 20' x 8' covered run and 3 egg nests. I live in Eastern Ontario where we get periods of temperatures under -20F/-30C (without windchill) in the winter and above 90F/30C and humid in the summer. I want the coop to work well for the chickens all year and avoid heating if possible, so ventilation has to be designed carefully...

For the summer it is relatively easy, I will just have panels on hinges that I can open on 3 sides (the north-facing side will be storage for the coop) with hardware cloth to keep predators out.

For the winter it is a lot trickier. Enough fresh air supply is required to get rid of moisture and ammonia, but there should not be any draft and retaining some heat is probably good as well.
So my plan is to seal the coop as well as possible and insulate the floor, the walls and above the ceiling, to prevent drafts and help retaining the heat. The coop will have a single window, facing south, and it will have a double glass panel for better insulation. I want the ceiling to be about 1 foot above the chickens so the volume of air around them is not excessive. I will use the deep liter method.
To flush the moisture and ammonia, I wanted to install a cupola on the roof, right in the middle of the coop, which will be linked to the coop through a 4" diameter pipe.

My understanding is that the above features are generally recommended for coops, so I am quite confident about them. Regarding the cupola, what I like about it is that it will directly extract  the lighter ammonia from the coop. Also, the pipe will have horizontal openings, such that winds should not generate drafts through that opening. The part that I am less confident about is what to do for air intake. I read recommendations about openings right under the roof, but I don't like the idea too much, because it will tend to make the coop colder and more drafty during windy days. An idea I have is to create vertical air intakes under the coop, which will sit 2' above the ground, and introduce that air in the coop about 1.5' above the floor (about 0.5' under the roost bars). I could have one air intake in each one of the four coop corners. Due to the location and orientation of these air intakes, it should be much less affected by winds, so the air would mostly get exchanged through convection, the 4" cupola pipe acting as a chimney. My plan is to have the same total cross-sectional area for the air intakes as for the 4" chimney. I would also make the opening of the 4" pipe adjustable, through hinged panels right above the ceiling.

I would like to know what you think of that design. How should such air intakes that are less sensitive to winds and that introduce air lower in the coop perform with chicken compared to openings under the roof. Should the cupola with a 4" pipe be sufficient for this 3.5' x 6' coop when it is too cold outside to open the wall panels?

Thank you!

Hi Pierre-Luc, and welcome to Permies.  

First, you know you get down to -40C at times.  It's OK, you can admit it. ;)  I know we get down to that most winters in SW ON, sometimes for a week or two.  

Insulation and ventilation are pretty much mutually exclusive.  It's nice to insulate the floor of the coop, but the deep litter takes care of that.  Also, they'll happily roam around in the snow, so it's usually not a big deal.  The window doesn't need to be double glazed as any heat in the coop will go right out the top.  You also don't need a fancy cupola, just know that you need to get rid of the excess moisture and, as you know, keep the drafts off them.

I built a 4x6' coop out of 2x3 frame on 2' centers and 1/2" ply sides and roof.  I slanted the roof from 7' to 5' and kept my roosts at 2.5-3' so there was about 18" above the roosting hen to the 2" gap around the roof.  I just ran 2x3" joists on top of the coop frame for the gap and used 1/2" hardware cloth to keep out rats, weasels and opossums.  I had a couple of open cut outs that I covered with hardware cloth for more ventilation in the summer that I covered in the winter.  

Chickens come with a down coat, so they can stay pretty warm in winter.  I chose breeds with small combs, pea combs for preference.  I had a number of Chanteclers, our only Canadian breed, and they do very well in winter, as you'd expect.  I did end up with a couple of hens with big combs and they did get a little frostbite, but not bad.  In winter, they'll crowd together on the roost for warmth, squat down on their feet and tuck they're heads under their wings.  If you heat the coop and then lose power, they can't handle the abrupt change, so that'll kill them.  I took my girls through several winters like that without any issues except frozen water and eggs.  

I built a cookie tin waterer heater for underneath the plastic waterer, though I had to use 2 75W bulbs when it got down below -20C.  If you do use a cupola, make your air intake the same gaps just below the roof.  That way you'll have air stratification and it will come in under the roof and out the cupola, but the cupola should be at least 2' tall to get the right stack effect.  I've done a lot of attic ventilation analyses and stratification is  normally a bad thing, but good for livestock.  Like I said, though, it's needlessly complicated as a 2" gap 18" above chicken height (2-2.5' above the roost) works just fine.

edit:  I just wanted to add that you pretty much need to supplement light in our winters as they like 14 hours to lay well, even the Chanteclers, whatever anyone tells you. If you get them this year as ready to lay or pullets, you don't have to let them moult in the fall but next year let them moult naturally as the light wanes, then add light back gradually in the morning to get to 14 hours.  You want them to experience natural dusk as they'll naturally go home to roost and the light won't shut off all of a sudden, leaving them on the floor.

My family had chickens in the 1970s in a log coop on the upper Yukon in Alaska, where it would get down below -50F and stay there for a couple of weeks at a time in January.  Under those conditions at least, ventilation was the enemy.  The goal was to seal that coop up as tightly as possible.  It was about six feet by eight feet, just tall enough for a person to stand inside, flat roof, made of about six inch logs, chinked with moss, plywood and tarpaper flat roof insulated with several inches of moss with Visqueen (plastic) vapor barrier.  There was sawdust on the floor of the coop but there was a screened bin under the perch to catch droppings.  Ammonia in the air was a definite issue, but never so much that it seemed to affect the health of the chickens.  I'm not saying any of this was a good way to do things, I'm just saying it was a way that worked and (mostly) kept chickens alive -- probably based on drawings/designs my parents saw in Mother Earth News magazine or Foxfire or a Rodale Press book.  

In the very coldest temperatures they would hang an old fashioned barn lantern (kerosine-fueled, metal lantern, wires protecting the glass chimney) from a nail just inside the door, well away from the perch.  It would provide a slight boost to the air temp in the coop.  

Chickens were a mix of "spent" factory egg layers (white leghorns with trimmed beaks and claws, very stupid birds, barely able to walk or scratch or feed themselves, apparently sold cheap in those days after their egg production would start to drop) and Rhode Island Reds that we raised from chicks bought as chicks.  The Reds had much larger combs and they did get a little bit of comb frostbite, but the Leghorns were much older birds.  My recollection is that we did get some mortality (one or two dead birds) among the leghorns the first winter when it got really cold.

I'm a huge fan of open air coops. In my opinion,  ventilation is far more important than temperature.  Woods' open air chicken coop book is fantastic.  

Chickens in very cold weather get frostbite.  They get frostbite far worse if there is any moisture at all in their coop. I kept chickens one year in a 3 sided coop i built from straw bales.  It didn't have a front at all.  It was narrow and pretty deep, I believe it was about 4 feet wide and 12 feet or so deep. I built the roof from old doors stacked across and resting on the side walls.  I put more bales on top of them for insulation.  I used tree branches at the very back for roosts.  Since the front was entirely open and i never water my chickens in their coop,  it stayed perfectly dry.  With the roosts in the very back,  they didn't get drafts.  The opening was facing south and our really cold winds come from the north east.  We had temps -15 to -20 regularly,  and a low as -30f . The chickens were fine and the rooster had almost no frostbite on his comb.  The rooster in my traditional coop got worse frostbite.  

Woods' book talks about the minimum depth the coop can be to keep the chickens away from drafts with a completely open air coop.

Other people mentioned snow.  My chickens won't walk in snow.  They don't mind the cold but none of the breeds I have raised would walk in snow. I build open ended greenhouse type structures to give mine areas to walk without snow in the winter.  That is also where their water is,  never in the coop.

Timothy Markus wrote:Hi Pierre-Luc, and welcome to Permies.  

First, you know you get down to -40C at times.  It's OK, you can admit it. ;)  I know we get down to that most winters in SW ON, sometimes for a week or two.

Ok yes I will admit it, it gets colder :-)  

Timothy Markus wrote:Insulation and ventilation are pretty much mutually exclusive.  It's nice to insulate the floor of the coop, but the deep litter takes care of that.  Also, they'll happily roam around in the snow, so it's usually not a big deal.  The window doesn't need to be double glazed as any heat in the coop will go right out the top.  You also don't need a fancy cupola, just know that you need to get rid of the excess moisture and, as you know, keep the drafts off them.

Yes I know that ventilation works against insulation, but I was hoping that insulation could still help a bit if I manage to constrain the ventilation to the necessary amount. I am also aware that some of the features I was considering are not a necessity, but I want to minimize the risks of frostbites. Using the 4" pipe that goes up to the cupola combined with vertical air intakes appeared to be a good way for me to control the amount of ventilation in a way that is less sensitive to wind.

Timothy Markus wrote:I built a 4x6' coop out of 2x3 frame on 2' centers and 1/2" ply sides and roof.  I slanted the roof from 7' to 5' and kept my roosts at 2.5-3' so there was about 18" above the roosting hen to the 2" gap around the roof.  I just ran 2x3" joists on top of the coop frame for the gap and used 1/2" hardware cloth to keep out rats, weasels and opossums.  I had a couple of open cut outs that I covered with hardware cloth for more ventilation in the summer that I covered in the winter.  

Chickens come with a down coat, so they can stay pretty warm in winter.  I chose breeds with small combs, pea combs for preference.  I had a number of Chanteclers, our only Canadian breed, and they do very well in winter, as you'd expect.  I did end up with a couple of hens with big combs and they did get a little frostbite, but not bad.  In winter, they'll crowd together on the roost for warmth, squat down on their feet and tuck they're heads under their wings.  If you heat the coop and then lose power, they can't handle the abrupt change, so that'll kill them.  I took my girls through several winters like that without any issues except frozen water and eggs.  

I built a cookie tin waterer heater for underneath the plastic waterer, though I had to use 2 75W bulbs when it got down below -20C.  If you do use a cupola, make your air intake the same gaps just below the roof.  That way you'll have air stratification and it will come in under the roof and out the cupola, but the cupola should be at least 2' tall to get the right stack effect.  I've done a lot of attic ventilation analyses and stratification is  normally a bad thing, but good for livestock.  Like I said, though, it's needlessly complicated as a 2" gap 18" above chicken height (2-2.5' above the roost) works just fine.

edit:  I just wanted to add that you pretty much need to supplement light in our winters as they like 14 hours to lay well, even the Chanteclers, whatever anyone tells you. If you get them this year as ready to lay or pullets, you don't have to let them moult in the fall but next year let them moult naturally as the light wanes, then add light back gradually in the morning to get to 14 hours.  You want them to experience natural dusk as they'll naturally go home to roost and the light won't shut off all of a sudden, leaving them on the floor.

Thanks for all the helpful information. I want to stay away from active heating. Regarding what you are saying about air stratification, do you mean that it would be better, if I have a design that involves a cupola, that the air intakes be located right under the roof instead of lower in the coop? Even if the intakes do not cause the coop to be drafty due to the air moving only through a controlled stack effect? The 4" pipe that would go to my cupola would be about 4' tall...

I intend to bring power to the coop to supplement light, warm up water, control doors, the ceiling vent and to monitor the temperature/humidity. The roof will have a 45 degree pitch and face south so it is ideal for solar panels in the future.

Dan Boone wrote:My family had chickens in the 1970s in a log coop on the upper Yukon in Alaska, where it would get down below -50F and stay there for a couple of weeks at a time in January.  Under those conditions at least, ventilation was the enemy.  The goal was to seal that coop up as tightly as possible.  It was about six feet by eight feet, just tall enough for a person to stand inside, flat roof, made of about six inch logs, chinked with moss, plywood and tarpaper flat roof insulated with several inches of moss with Visqueen (plastic) vapor barrier.  There was sawdust on the floor of the coop but there was a screened bin under the perch to catch droppings.  Ammonia in the air was a definite issue, but never so much that it seemed to affect the health of the chickens.  I'm not saying any of this was a good way to do things, I'm just saying it was a way that worked and (mostly) kept chickens alive -- probably based on drawings/designs my parents saw in Mother Earth News magazine or Foxfire or a Rodale Press book.  

In the very coldest temperatures they would hang an old fashioned barn lantern (kerosine-fueled, metal lantern, wires protecting the glass chimney) from a nail just inside the door, well away from the perch.  It would provide a slight boost to the air temp in the coop.  

Chickens were a mix of "spent" factory egg layers (white leghorns with trimmed beaks and claws, very stupid birds, barely able to walk or scratch or feed themselves, apparently sold cheap in those days after their egg production would start to drop) and Rhode Island Reds that we raised from chicks bought as chicks.  The Reds had much larger combs and they did get a little bit of comb frostbite, but the Leghorns were much older birds.  My recollection is that we did get some mortality (one or two dead birds) among the leghorns the first winter when it got really cold.

Thanks for sharing your experience. -50F in Alaska is definitely more extreme than here. If you say that ammonia was an issue, do you think they were also affected by moisture as well under these conditions?

Trace Oswald wrote:I'm a huge fan of open air coops. In my opinion,  ventilation is far more important than temperature.  Woods' open air chicken coop book is fantastic.  

Chickens in very cold weather get frostbite.  They get frostbite far worse if there is any moisture at all in their coop. I kept chickens one year in a 3 sided coop i built from straw bales.  It didn't have a front at all.  It was narrow and pretty deep, I believe it was about 4 feet wide and 12 feet or so deep. I built the roof from old doors stacked across and resting on the side walls.  I put more bales on top of them for insulation.  I used tree branches at the very back for roosts.  Since the front was entirely open and i never water my chickens in their coop,  it stayed perfectly dry.  With the roosts in the very back,  they didn't get drafts.  The opening was facing south and our really cold winds come from the north east.  We had temps -15 to -20 regularly,  and a low as -30f . The chickens were fine and the rooster had almost no frostbite on his comb.  The rooster in my traditional coop got worse frostbite.  

Woods' book talks about the minimum depth the coop can be to keep the chickens away from drafts with a completely open air coop.

Other people mentioned snow.  My chickens won't walk in snow.  They don't mind the cold but none of the breeds I have raised would walk in snow. I build open ended greenhouse type structures to give mine areas to walk without snow in the winter.  That is also where their water is,  never in the coop.

Thanks for the book recommendation, I will look it up. Regarding the moisture issue, do you think that the deep liter method might be a bad idea for a non open air coop in cold temperatures? Also I am wondering how coops that exchange air through wall openings perform compared to coops that do it using a stack effect... In my area it tends to get really windy sometimes so this is why I was looking for a design that is not sensitive to wind.

Pierre-Luc Drouin wrote:
Thanks for sharing your experience. -50F in Alaska is definitely more extreme than here. If you say that ammonia was an issue, do you think they were also affected by moisture as well under these conditions?

I was a little kid, which is why I'm trying to recount my memories of how the coop was set up and that the chickens survived, without getting too detailed about their health details, which I probably never knew or was competent to assess; if it got discussed, those discussions might not have happened in my earshot.  I mention the ammonia because I remember the stink being fierce, and I know with my adult knowledge now that this is from ammonia, and that my mother was not managing the droppings as most do today in a deep/dry litter, but rather was letting them accumulate wet in a bin under the perch, screened with chicken wire to keep the birds out and to catch any eggs that the really-very-stupid leghorns (not their fault, they were raised in factory boxes where they never got to move) laid from the perch.  

There was not much egg production once the sun went down late November for its six week nap.  I don't think it ever completely stopped, but it dropped off to just a few eggs a day out of close to 20 hens.

I don't remember the ammonia being/causing any problems, health-wise, for the chickens.  Which is not to say that it didn't.  

Moisture, I don't think, was a problem.  Interior Alaska winters are extremely dry.  You can spot your air leaks in a cabin in cold weather by the streaks of frost around all the places warm wet air is leaking out.  The chicken coop, being below freezing but much warmer than outside, got some frost buildup on some of the interior surfaces; we would brush those frost crystals off the ceiling with our mittens (to avoid getting them down our necks) and they would mix with the sawdust on the floor.  I'm not sure how often the droppings box got shoveled out but I am fairly sure that sawdust got changed or at least layered fairly frequently, because we kids tracked through it to feed the chickens and check for eggs, and mom didn't want droppings tracked back into the house, even frozen.  

I know this is a long way away from your situation and design.  But I hope the knowledge that chickens are pretty extreme in what they can handle, helps reassure you that your much more modern designs will probably work out excellently!

While we don't hit -20 here often in PA usa we we're at 0 a few times this winter an my chickens did fine. My run is 14*10 with old chain link fencing. I simply secured cheap plastic tarps to 3 of the sides from the direction of the wind to create a wind block an stop snow from being blown in and they have a coop box off the side that 3*3 with 3nest boxes but they seemed to prefer roosting out in the run most of the non windy nights. I also have my rabbit cages hanging in the run to use up the extra space an they also did just fine. We had a terrible winter here where it was 40 one day everything was wet then the next day 15 everything frozen solid.
Wind protection, dry area for them to walk in, an a shelter or coop to go into for the extreme days you should be good.

Pierre-Luc Drouin wrote:
Thanks for all the helpful information. I want to stay away from active heating. Regarding what you are saying about air stratification, do you mean that it would be better, if I have a design that involves a cupola, that the air intakes be located right under the roof instead of lower in the coop? Even if the intakes do not cause the coop to be drafty due to the air moving only through a controlled stack effect? The 4" pipe that would go to my cupola would be about 4' tall...

I intend to bring power to the coop to supplement light, warm up water, control doors, the ceiling vent and to monitor the temperature/humidity. The roof will have a 45 degree pitch and face south so it is ideal for solar panels in the future.

As long as you don't have drafts, whatever you do will be fine if it provides enough ventilation.  The cupola and the air intakes will work but are, in my experience, needlessly complicated.  I got excellent ventilation from about a 2" screened gap just below the roof around all four walls with the low point of the roof pointed to the prevailing winds.  Ammonia will rise, so that's helpful.  If you're set on a cupola you can do what you've suggested or just use openings just under the roof, but you'd need a cupola of at least 2'above the intake in order to get enough stack effect for the ventilation to work.  If you put intake on the low side of the roof and the cupola at the top side, the rise will count towards that two feet.

I re-read your bit about the intakes:

An idea I have is to create vertical air intakes under the coop, which will sit 2' above the ground, and introduce that air in the coop about 1.5' above the floor (about 0.5' under the roost bars).  

 You want the air intake above the chickens, not below, as that would cause drafts from bottom to top.  I like air intake to be about 18" above the chickens when roosting.  I never bothered to calculate air changes, I just gave them enough ventilation to make sure it was fresh air.  If your roof only has a single slope, you need your air egress at the top of the slope.  If you put a cupola in the middle, the ammonia can pool in the upslope of the ceiling.

Trace Oswald wrote:I'm a huge fan of open air coops. In my opinion,  ventilation is far more important than temperature.  Woods' open air chicken coop book is fantastic.  

Chickens in very cold weather get frostbite.  They get frostbite far worse if there is any moisture at all in their coop. I kept chickens one year in a 3 sided coop i built from straw bales.  It didn't have a front at all.  It was narrow and pretty deep, I believe it was about 4 feet wide and 12 feet or so deep. I built the roof from old doors stacked across and resting on the side walls.  I put more bales on top of them for insulation.  I used tree branches at the very back for roosts.  Since the front was entirely open and i never water my chickens in their coop,  it stayed perfectly dry.  With the roosts in the very back,  they didn't get drafts.  The opening was facing south and our really cold winds come from the north east.  We had temps -15 to -20 regularly,  and a low as -30f . The chickens were fine and the rooster had almost no frostbite on his comb.  The rooster in my traditional coop got worse frostbite.  

Woods' book talks about the minimum depth the coop can be to keep the chickens away from drafts with a completely open air coop.

Other people mentioned snow.  My chickens won't walk in snow.  They don't mind the cold but none of the breeds I have raised would walk in snow. I build open ended greenhouse type structures to give mine areas to walk without snow in the winter.  That is also where their water is,  never in the coop.

We’re in upper Michigan in the midst of our first winter with chickens. Its single digits as a high right now and about -15 at night for the next 10 days. We’ve got a 4x8 coop with 7 Orpingtons in it. Several of them have gotten frostbite twice now on their combs and I’m thinking that they could use more ventilation above the roost. But I don’t know if there’s enough space between their heads and the roof to provide more ventilation without giving them drafts. Apparently I designed the coop with 3 seasons in mind and didn’t consider winter ventilation as much as i should have. I just dont know of their frostbite is coming from too much moisture/not enough ventilation, or if its from a draft too close to their heads while they sleep. I never kept food or water in the coop until now, and always turned the light off after dark. Now theres food and a bowl of snow for them in the coop and I left the light on last night. This morning, the coop was 6 above and outside was -15. I hear constant light stresses the birds, but that 21 degree difference makes me wonder if its worth it.

Also, ours dont particularly like snow either. We shovel them paths and sometimes they still arent too adventurous.

Here in Thunder Bay where it gets this cold it is essential to keep the ammonia down for starters. The trick with that is making sure the watering system is a type that is clean and doesn't spread water in the bedding. It will also need heating so it doesn't freeze.

If you use a deep straw bed then their manure will break down slowly and release some heat, but because it's dry it won't smell or get all compacted and disgusting.

And that is pretty much all they need. A heat lamp is good not just for heat but also for light which in the winter time they really need for egg production.

An exit into an outside run which is placed at a low point so the warm air in the coop doesn't escape also helps and you'd be surprised at how active they are outside even when it's super cold.

I'm building a henhouse for my first flock next spring. I've read a bunch of conflicting stuff about insulating vs. ventilating in other places and it occurred to me to come search here to help break the ties. Sadly, y'all mimic the conflict that I see everywhere. I guess I'm going to have to build with large hardware-clothed windows and just have 3" foam inserts to shove between the studs so I can go either way and decide day by day how open things should be. I also hope to avoid electric heating, except maybe for water, but our low last winter was -36F and I sure don't want to hurt my animals.

Christopher Weeks wrote:I'm building a henhouse for my first flock next spring. I've read a bunch of conflicting stuff about insulating vs. ventilating in other places and it occurred to me to come search here to help break the ties. Sadly, y'all mimic the conflict that I see everywhere. I guess I'm going to have to build with large hardware-clothed windows and just have 3" foam inserts to shove between the studs so I can go either way and decide day by day how open things should be. I also hope to avoid electric heating, except maybe for water, but our low last winter was -36F and I sure don't want to hurt my animals.

Christopher, if you read Woods' book, it may alleviate some of your concerns.  The book is available free in PDF format due to it's age.  Here it is in one place:  Modern Fresh Air Poultry Houses   I designed my newest coop from that book.  Your climate is very similar to mine here in Wisconsin.  My bird have done fine through two nights of -40 and many, many nights of -20 to -30 with no heat.  Like you, I've seen it debated nearly endlessly, but I've never seen open air, non-insulated coops debated against except by people that have never tried it.  I've yet to read a single account of someone that actually tried one and then decided it didn't work well.  

If you decide you are more comfortable insulating, nothing says you can't make foam inserts for your windows.  If you decide to go that route, I would give two pieces of advice I learned from putting insulation in a previous coop.  First, if you put insulation anywhere the birds can get, they will pick it to pieces in no time, so I would cover the pieces with very thin plywood or layers of duct tape or something to stop that.  Second, if you get any moisture build up or smells whatsoever, I would remove them immediately and let the coop dry out very well.  I've never had a coop too dry, but any amount of dampness will cause lung issues in your birds.  The only birds I have lost other than to predation were due to lung issues from damp and/or ammonia.  For me, it went like this:  Most of the winter, everything in the coop was frozen, so there were no issues.  The first slightly warm day, it would thaw everything in the coop and the ammonia would build up very, very quickly, along with a large increase in dampness.  I would have to add 6 or 7 bales of wood shavings at once to combat it and even that didn't work well.  That lead to lung issues and I lost some birds that way.  After quite a few years of doing this, I'm convinced that dampness is your chickens' worst enemy.

Trace Oswald wrote:
Christopher, if you read Woods' book, it may alleviate some of your concerns.  The book is available free in PDF format due to it's age.  Here it is in one place:  Modern Fresh Air Poultry Houses   I designed my newest coop from that book.  Your climate is very similar to mine here in Wisconsin.  My bird have done fine through two nights of -40 and many, many nights of -20 to -30 with no heat.  Like you, I've seen it debated nearly endlessly, but I've never seen open air, non-insulated coops debated against except by people that have never tried it.  I've yet to read a single account of someone that actually tried one and then decided it didn't work well.  

Trace, where in Wisconsin are you? We live in Iron River MI about 7 miles from the Wisconsin border. We get -30 or so most winters as well. Do you guys get much snow where you’re at? I ask because I’m trying to imagine how an open air coop would work in the winter with blowing, drifting snow. Obviously, facing the open end 180 degrees away from the prevailing winds would be the way to go, but wouldn’t blowing snow drift over the roof and curl into the open side of the coop?

I haven’t looked into the design much because we’re only a year and a half into raising chickens, but I will check out the link you provided in case he addresses that. I learned the hard way last winter how important ventilation is. All 7 of our chickens got frost bitten combs twice. Once I blocked the drafty windows better and added more ventilation up above they seemed to do better.

Brody Ekberg wrote:

Trace Oswald wrote:
Christopher, if you read Woods' book, it may alleviate some of your concerns.  The book is available free in PDF format due to it's age.  Here it is in one place:  Modern Fresh Air Poultry Houses   I designed my newest coop from that book.  Your climate is very similar to mine here in Wisconsin.  My bird have done fine through two nights of -40 and many, many nights of -20 to -30 with no heat.  Like you, I've seen it debated nearly endlessly, but I've never seen open air, non-insulated coops debated against except by people that have never tried it.  I've yet to read a single account of someone that actually tried one and then decided it didn't work well.  

Trace, where in Wisconsin are you? We live in Iron River MI about 7 miles from the Wisconsin border. We get -30 or so most winters as well. Do you guys get much snow where you’re at? I ask because I’m trying to imagine how an open air coop would work in the winter with blowing, drifting snow. Obviously, facing the open end 180 degrees away from the prevailing winds would be the way to go, but wouldn’t blowing snow drift over the roof and curl into the open side of the coop?

I haven’t looked into the design much because we’re only a year and a half into raising chickens, but I will check out the link you provided in case he addresses that. I learned the hard way last winter how important ventilation is. All 7 of our chickens got frost bitten combs twice. Once I blocked the drafty windows better and added more ventilation up above they seemed to do better.

I'm on the other side of the state near the Minnesota side.  We get lots of snow.  The way the open air coops work, they keep most of the snow from coming in.  You may get a little at the very front, but not much, and not often.  As you said, the rear of the coop faces into the cold winds and blocks the cold wind and snow from coming in.

The design of open air coops is pretty specific.  You don't really want ventilation above your chickens.  If you have an open front and any opening at the top, you create a chimney effect that draws cold air in the front, along with snow and whatever else, and out through the openings in the top.  That creates a cold draft right through your coop and cold weather + drafts = bad.  The easiest way for me to picture a properly built open air coop is to picture a long narrow cave.  The front is entirely open, but since the back and top of the cave is airtight, no drafts can penetrate the cave.  There is plenty of ventilation from the open front, but air trying to blow to the back is stopped because there is no outlet for it.  If you built a room that was 6' wide and 6' tall, but 20' deep, and stood at the very back, closed, end of the room, even on a very windy day, you wouldn't feel a breeze.  Also, the back part of the coop is larger than the front, so it creates a large air pocket in the area where the chickens roost.  In the summer, you open windows in the upper part of the coop and create that chimney effect.  That lets cooler air come in the front and pass through the coop and the warmer air goes out the windows, so you create a breeze that cools and dries the coop.  It's a pretty fascinating design I think.

Trace Oswald wrote:
The design of open air coops is pretty specific.  You don't really want ventilation above your chickens.  If you have an open front and any opening at the top, you create a chimney effect that draws cold air in the front, along with snow and whatever else, and out through the openings in the top.  That creates a cold draft right through your coop and cold weather + drafts = bad.  The easiest way for me to picture a properly built open air coop is to picture a long narrow cave.  The front is entirely open, but since the back and top of the cave is airtight, no drafts can penetrate the cave.  There is plenty of ventilation from the open front, but air trying to blow to the back is stopped because there is no outlet for it.  If you built a room that was 6' wide and 6' tall, but 20' deep, and stood at the very back, closed, end of the room, even on a very windy day, you wouldn't feel a breeze.  Also, the back part of the coop is larger than the front, so it creates a large air pocket in the area where the chickens roost.  In the summer, you open windows in the upper part of the coop and create that chimney effect.  That lets cooler air come in the front and pass through the coop and the warmer air goes out the windows, so you create a breeze that cools and dries the coop.  It's a pretty fascinating design I think.

Ill have to look into it more deeply for my next coop build. Currently, our little 4x8 coop isn’t airtight, but most of the air spaces are above the chickens head level while they are roosted, which is also the level of the ventilation. So, most of the moving air should be above them, but the design is far from perfect.

One concern I would have with one full wall being open is the oddball days where the wind switches. Most of our winter winds come from the northwest, so the open end would be towards the southeast, but we do get south winds sometimes and there would be no good way to block that from entering the coop. I suppose even just some cardboard or a tarp could be used for a night if necessary.

Brody Ekberg wrote:

Ill have to look into it more deeply for my next coop build. Currently, our little 4x8 coop isn’t airtight, but most of the air spaces are above the chickens head level while they are roosted, which is also the level of the ventilation. So, most of the moving air should be above them, but the design is far from perfect.

One concern I would have with one full wall being open is the oddball days where the wind switches. Most of our winter winds come from the northwest, so the open end would be towards the southeast, but we do get south winds sometimes and there would be no good way to block that from entering the coop. I suppose even just some cardboard or a tarp could be used for a night if necessary.

If your coop isn't air tight, I think you may have a problem having vents above the chickens because any heat they create with their bodies will cause the air in the coop to rise and go out through the vents.  This will cause cold air to be pulled in from any nook or cranny that isn't sealed anywhere else in the coop.  

I may not have explained well how the open wall works.  Even if it the opening faced directly into the wind, the wind can't enter the coop if it is a longer, narrower shape.  When the wind tries to blow into the open wall, it has no escape route at the other end of the coop and the air pressure keeps the wind from entering.  Wind can't go into the coop if it has nowhere to exit.  That's why these coops are built relatively long and narrow.  In a 4'x8' coop, that probably isn't the case.

Trace Oswald wrote:
If your coop isn't air tight, I think you may have a problem having vents above the chickens because any heat they create with their bodies will cause the air in the coop to rise and go out through the vents.  This will cause cold air to be pulled in from any nook or cranny that isn't sealed anywhere else in the coop.  

I may not have explained well how the open wall works.  Even if it the opening faced directly into the wind, the wind can't enter the coop if it is a longer, narrower shape.  When the wind tries to blow into the open wall, it has no escape route at the other end of the coop and the air pressure keeps the wind from entering.  Wind can't go into the coop if it has nowhere to exit.  That's why these coops are built relatively long and narrow.  In a 4'x8' coop, that probably isn't the case.

Ive got too much to do between now and winter to build a new coop, so I will just see how the chickens do this winter with the few changes I made. I was noticing last year that the inside of the coop was roughly 7-10 degrees warmer than the outside temperature just from their body heat. But that was before I added more ventilation.

I am fascinated with the idea that air wont blow into these coops though, even if blowing directly at the open side. I’m picturing myself in a north facing cave during a north wind and having a hard time believing I wouldn’t feel the wind. Or with the same logic, if I put a feather in the bottom of a deep glass and I try to blow the feather around, it shouldn’t move much right? Same concept. Ill have to give that a try later!

Brody Ekberg wrote:

Trace Oswald wrote:
If your coop isn't air tight, I think you may have a problem having vents above the chickens because any heat they create with their bodies will cause the air in the coop to rise and go out through the vents.  This will cause cold air to be pulled in from any nook or cranny that isn't sealed anywhere else in the coop.  

I may not have explained well how the open wall works.  Even if it the opening faced directly into the wind, the wind can't enter the coop if it is a longer, narrower shape.  When the wind tries to blow into the open wall, it has no escape route at the other end of the coop and the air pressure keeps the wind from entering.  Wind can't go into the coop if it has nowhere to exit.  That's why these coops are built relatively long and narrow.  In a 4'x8' coop, that probably isn't the case.

Ive got too much to do between now and winter to build a new coop, so I will just see how the chickens do this winter with the few changes I made. I was noticing last year that the inside of the coop was roughly 7-10 degrees warmer than the outside temperature just from their body heat. But that was before I added more ventilation.

I am fascinated with the idea that air wont blow into these coops though, even if blowing directly at the open side. I’m picturing myself in a north facing cave during a north wind and having a hard time believing I wouldn’t feel the wind. Or with the same logic, if I put a feather in the bottom of a deep glass and I try to blow the feather around, it shouldn’t move much right? Same concept. Ill have to give that a try later!

Take the cardboard from a paper towel roll, hold your hand over one end, and try to blow into the other :)   Obviously it doesn't work exactly like that, but yes, I would assume your thoughts are correct.  If the glass is deep and narrow enough, the feather shouldn't move around much.  I think a better experiment would be putting a feather in something like a test tube and trying to blow the feather out.  

I also think there is definitely a "sweet spot" with regards to length vs cross sectional area.  The book outlines the minimum depth for a given size.  It also makes sense to me that if you went past a certain point, you would lose the advantage of having a open front.  In actual practice, it would probably never happen, but to try to picture these things in my mind, I sometimes exaggerate to a ridiculous degree to see if it makes sense.  In that light, suppose I made a coop that was 6'x6' but 200' long.  I'm quite certain I wouldn't get breezes at the back of the coop, but the extreme length may negate the open wall and I may get little to no fresh air either.  

Another thing is to keep in mind that the rear of the coop has a much higher ceiling than the front, and so will also create a "dead air" space.  If you open the windows, that space disappears, but with them tightly closed, I wouldn't expect much if any air movement in that area.

I'm about halfway finished with my new coop.  I stopped working on it when prices went crazy, but they are dropping somewhat now, so I'll probably start on it again soon.  The new one is 8'x16' and I'm really happy with the way it is coming along.  I'll post about that one when I have had a chance to have it up and running for some amount of time.

Trace Oswald wrote:
Another thing is to keep in mind that the rear of the coop has a much higher ceiling than the front, and so will also create a "dead air" space.  If you open the windows, that space disappears, but with them tightly closed, I wouldn't expect much if any air movement in that area.

I'm about halfway finished with my new coop.  I stopped working on it when prices went crazy, but they are dropping somewhat now, so I'll probably start on it again soon.  The new one is 8'x16' and I'm really happy with the way it is coming along.  I'll post about that one when I have had a chance to have it up and running for some amount of time.

I’m just trying to get this all straight so correct me if I’m wrong:

The front of the coop is the open side

The back of the coop has a significantly higher ceiling

The roosts are in the back

Wouldn’t that mean that the most stagnant and humid air is around the roosts and the fresh air is farthest from the sleeping chickens? I see how opening a window above the roosts would help a lot, but I wonder what the balance would be in open vs closed during winter. Our chickens are almost always outside anyway except for at night.

Brody Ekberg wrote:

Trace Oswald wrote:
Another thing is to keep in mind that the rear of the coop has a much higher ceiling than the front, and so will also create a "dead air" space.  If you open the windows, that space disappears, but with them tightly closed, I wouldn't expect much if any air movement in that area.

I'm about halfway finished with my new coop.  I stopped working on it when prices went crazy, but they are dropping somewhat now, so I'll probably start on it again soon.  The new one is 8'x16' and I'm really happy with the way it is coming along.  I'll post about that one when I have had a chance to have it up and running for some amount of time.

I’m just trying to get this all straight so correct me if I’m wrong:

The front of the coop is the open side

The back of the coop has a significantly higher ceiling

The roosts are in the back

Wouldn’t that mean that the most stagnant and humid air is around the roosts and the fresh air is farthest from the sleeping chickens? I see how opening a window above the roosts would help a lot, but I wonder what the balance would be in open vs closed during winter. Our chickens are almost always outside anyway except for at night.

Yes, the front of the coop is open, the back is the nesting area.  The front open area is large enough that the air in the back doesn't get stagnant and it stays very dry, but doesn't have drafts.  No humidity builds up.  Like yours, my chickens are out during the day if they want to be.  I have covered areas they can walk around in during the day.  Mine don't seem to mind the cold, but they don't like to walk in the snow, so I make sheltered areas for them that are open at the ends so they are completely fresh air but without snow.  Mine are just very basic hoop houses built from cattle panels with plastic coverings.  

Trace Oswald wrote:Christopher, if you read Woods' book, it may alleviate some of your concerns.  The book is available free in PDF format due to it's age.  Here it is in one place:  Modern Fresh Air Poultry Houses   I designed my newest coop from that book.  Your climate is very similar to mine here in Wisconsin.  My bird have done fine through two nights of -40 and many, many nights of -20 to -30 with no heat.  Like you, I've seen it debated nearly endlessly, but I've never seen open air, non-insulated coops debated against except by people that have never tried it.  I've yet to read a single account of someone that actually tried one and then decided it didn't work well.  

Trace, thanks so much! I read enough of that PDF that I knew I wanted to the book, so I bought a copy and just finished reading through it. I'm convinced. But I don't have the freedom to build completely to his plans, having already excavated a pit for litter and assembled the floating foundation, so I'm going to figure out how to adapt my plans to the open-front goals. I wish I'd read this book two years ago. (Future readers of this thread -- read the book!)

I built the small size Woods house which is 6x10 and according to the author can accommodate 12-15 birds. I currently have 14 birds in there but during summer I had 24 at one point. I feel that 14 is too much during winter because the chickens don't go outside, 10 would be better.

January/Febuary are our coldest months with lots of nights in the -20F. One rooster got frostbite on its large comb and wattles, the others are ok. His problems don't come from the coop design, he's just not suited for the climate here.

The coop has no floor, is not insulated and not powered (no heat and no light).  I spent some time in there with the chickens during a bad winter storm, the air inside was perfectly calm. I keep the windows covered with plastic but the front is always open. I've never seen any signs of condensation or frost.

If it smells when the ground thaws I add more shavings. In spring I empty the coop and put new shavings for a fresh start. I dump everything in the run to start the compost pile.  I can hear the doubt when I mention my coop in unheated. I've visited a couple of heated coops and I understand the concern. Without electricity I don't think those coops would work, and the stink!

I never had chickens that liked snow. This fall I bough a hay bale and when it's nice outside I'll spread some in the run and they like it a lot.

Francis Mallet wrote:I built the small size Woods house which is 6x10 and according to the author can accommodate 12-15 birds. I currently have 14 birds in there but during summer I had 24 at one point. I feel that 14 is too much during winter because the chickens don't go outside, 10 would be better.

January/Febuary are our coldest months with lots of nights in the -20F. One rooster got frostbite on its large comb and wattles, the others are ok. His problems don't come from the coop design, he's just not suited for the climate here.

The coop has no floor, is not insulated and not powered (no heat and no light).  I spent some time in there with the chickens during a bad winter storm, the air inside was perfectly calm. I keep the windows covered with plastic but the front is always open. I've never seen any signs of condensation or frost.

If it smells when the ground thaws I add more shavings. In spring I empty the coop and put new shavings for a fresh start. I dump everything in the run to start the compost pile.  I can hear the doubt when I mention my coop in unheated. I've visited a couple of heated coops and I understand the concern. Without electricity I don't think those coops would work, and the stink!

I never had chickens that liked snow. This fall I bough a hay bale and when it's nice outside I'll spread some in the run and they like it a lot.

Very nice coop! I’m looking to build the Woods 6x10 coop this summer. Did you follow the plans in the Modern Fresh Air Poultry Houses book exactly or did you tweak the plans to account for  sheets of plywood and modern lumber dimensions?

my birds survived with light frostbite on their combs - 40f 3xs and -43f 1x this winter. no heat with open eaves in a 10' x10' coop and they still layed eggs but much less due to the extreme cold. i also keep the water outside so humidity doesnt build up from the steam in there. they drink quickly then eat snow until i water them again. im in N. Maine on the New Brunswick border across from Edmonston, N.B. and by the way, anyone that says leghorns aren't cold hardy, they weren't in any worse shape than my bigger breeds and continued to lay when the others stopped. i dont do light in the winter.

Francis Mallet wrote:I built the small size Woods house which is 6x10 and according to the author can accommodate 12-15 birds. I currently have 14 birds in there but during summer I had 24 at one point. I feel that 14 is too much during winter because the chickens don't go outside, 10 would be better.

January/Febuary are our coldest months with lots of nights in the -20F. One rooster got frostbite on its large comb and wattles, the others are ok. His problems don't come from the coop design, he's just not suited for the climate here.

The coop has no floor, is not insulated and not powered (no heat and no light).  I spent some time in there with the chickens during a bad winter storm, the air inside was perfectly calm. I keep the windows covered with plastic but the front is always open. I've never seen any signs of condensation or frost.

If it smells when the ground thaws I add more shavings. In spring I empty the coop and put new shavings for a fresh start. I dump everything in the run to start the compost pile.  I can hear the doubt when I mention my coop in unheated. I've visited a couple of heated coops and I understand the concern. Without electricity I don't think those coops would work, and the stink!

I never had chickens that liked snow. This fall I bough a hay bale and when it's nice outside I'll spread some in the run and they like it a lot.

i too put down some hay. on nicer days i open the door and let them wander where i snowblow.

Brody Ekberg wrote:Very nice coop! I’m looking to build the Woods 6x10 coop this summer. Did you follow the plans in the Modern Fresh Air Poultry Houses book exactly or did you tweak the plans to account for  sheets of plywood and modern lumber dimensions?

I improvised to fit plywood and to use what I had on hand. I can't say it's a clean build, lots of little annoying details popping up as I went along. I built the walls inside my workshop and I forgot to account for the thickness of the shop doors when open. Three inches taller and the chickens would now live in the shop  lol

It's a nice looking coop although for my next one I'd like to find a simpler, cheaper design.

This link is from the guy who publishes the book I got:
FAQ: Chicken Coops

Francis Mallet wrote:

Brody Ekberg wrote:Very nice coop! I’m looking to build the Woods 6x10 coop this summer. Did you follow the plans in the Modern Fresh Air Poultry Houses book exactly or did you tweak the plans to account for  sheets of plywood and modern lumber dimensions?

I improvised to fit plywood and to use what I had on hand. I can't say it's a clean build, lots of little annoying details popping up as I went along. I built the walls inside my workshop and I forgot to account for the thickness of the shop doors when open. Three inches taller and the chickens would now live in the shop  lol

It's a nice looking coop although for my next one I'd like to find a simpler, cheaper design.

This link is from the guy who publishes the book I got:
FAQ: Chicken Coops

What sort of “little annoying details” kept popping up? I ask because I have very little building experience and want to build this coop this summer. Ive already got loads of rough cut red pine lumber for the framing and for siding it so expenses shouldn’t be bad aside for roofing, plywood, windows and little miscellaneous things.

My lumber is between 1.75x3.75” and a literal 2”x4”, so different from dimensional lumber in stores. I have no idea what the original Woods coops were built with. I would assume lumber sizes weren't a lie back then but I really don't know. So, im wondering if I will run into issues if I just use my lumber and follow the blueprint or if I should try to think the whole thing through and make adjustments based off of size differences.

Brody Ekberg wrote:
What sort of “little annoying details” kept popping up? I ask because I have very little building experience and want to build this coop this summer. Ive already got loads of rough cut red pine lumber for the framing and for siding it so expenses shouldn’t be bad aside for roofing, plywood, windows and little miscellaneous things.

My lumber is between 1.75x3.75” and a literal 2”x4”, so different from dimensional lumber in stores. I have no idea what the original Woods coops were built with. I would assume lumber sizes weren't a lie back then but I really don't know. So, im wondering if I will run into issues if I just use my lumber and follow the blueprint or if I should try to think the whole thing through and make adjustments based off of size differences.

I'm sorry I took so long to answer. Details like the exact size and placement of the doors, window openings, roosts, laying boxes, etc. Also how to frame the coop to fit the plywood pieces without excessive waste. How to make the windows, how much overhang, how to finish the roof (eaves, fascia? whatever those parts are called in English).  The plan I had was more of a guideline than a complete plan you can follow from start to finish. I like to build stuff but I'm not fond of making plans so I tend to improvise. It goes well at first but then all the little mistakes tend to add up in the end.

Actual lumber size doesn't matter that much. Use the straight ones where the plywood sheets meet and try to get a bunch that are the same size for the roof.

I think I said this before, my coop looks good and works great but the next one will be a simple lean-to style shed with an open front, tin roof and no floor.